1 /*
2 * Copyright (c) 2024, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package jdk.incubator.code.analysis;
27
28 import jdk.incubator.code.*;
29 import jdk.incubator.code.op.CoreOp;
30 import jdk.incubator.code.type.*;
31
32 import java.util.*;
33
34 /**
35 * StringConcatTransformer is an {@link java.lang.reflect.code.OpTransformer} that removes concatenation operations
36 * from blocks and replaces them with equivalent {@link java.lang.StringBuilder} operations. This provides a pathway
37 * to remove {@link java.lang.reflect.code.op.CoreOp.ConcatOp} for easier lowering to Bytecode.
38 */
39 public final class StringConcatTransformer implements OpTransformer {
40
41 private static final JavaType J_L_STRING_BUILDER = JavaType.type(StringBuilder.class);
42 private static final MethodRef SB_TO_STRING_REF = MethodRef.method(
43 J_L_STRING_BUILDER, "toString", JavaType.J_L_STRING);
44
45 public StringConcatTransformer() {}
46
47 @Override
48 public Block.Builder apply(Block.Builder block, Op op) {
49 switch (op) {
50 case CoreOp.ConcatOp cz when isRootConcat(cz) -> {
51 // Create a string builder and build by traversing tree of operands
52 Op.Result builder = block.apply(CoreOp._new(ConstructorRef.constructor(J_L_STRING_BUILDER)));
53 buildFromTree(block, builder, cz);
54 // Convert to string
55 Value s = block.op(CoreOp.invoke(SB_TO_STRING_REF, builder));
56 block.context().mapValue(cz.result(), s);
57 }
58 case CoreOp.ConcatOp _ -> {
59 // Process later when building from root concat
60 }
61 default -> block.op(op);
62 }
63 return block;
64 }
65
66 static boolean isRootConcat(CoreOp.ConcatOp cz) {
67 // Root of concat tree, zero uses, two or more uses,
68 // or one use that is not a subsequent concat op
69 Set<Op.Result> uses = cz.result().uses();
70 return uses.size() != 1 || !(uses.iterator().next().op() instanceof CoreOp.ConcatOp);
71 }
72
73 static void buildFromTree(Block.Builder block, Op.Result builder, CoreOp.ConcatOp cz) {
74 // Process concat op's operands from left to right
75 buildFromTree(block, builder, cz.operands().get(0));
76 buildFromTree(block, builder, cz.operands().get(1));
77 }
78
79 static void buildFromTree(Block.Builder block, Op.Result builder, Value v) {
80 if (v instanceof Op.Result r &&
81 r.op() instanceof CoreOp.ConcatOp cz &&
82 r.uses().size() == 1) {
83 // Node of tree, recursively traverse the operands
84 buildFromTree(block, builder, cz);
85 } else {
86 // Leaf of tree, append value to builder
87 // Note leaf can be the result of a ConcatOp with multiple uses
88 block.op(append(block, builder, block.context().getValue(v)));
89 }
90 }
91
92 private static Op append(Block.Builder block, Value builder, Value arg) {
93 // Check if we need to widen unsupported integer types in the StringBuilder API
94 // Strings are fed in as-is, everything else given as an Object.
95 TypeElement type = arg.type();
96 if (type instanceof PrimitiveType) {
97 //Widen Short and Byte to Int.
98 if (type.equals(JavaType.BYTE) || type.equals(JavaType.SHORT)) {
99 arg = block.op(CoreOp.conv(JavaType.INT, arg));
100 type = JavaType.INT;
101 }
102 } else if (!type.equals(JavaType.J_L_STRING)){
103 type = JavaType.J_L_OBJECT;
104 }
105
106 MethodRef methodDesc = MethodRef.method(J_L_STRING_BUILDER, "append", J_L_STRING_BUILDER, type);
107 return CoreOp.invoke(methodDesc, builder, arg);
108 }
109
110
111 }